Frozen Pipes: How to Prevent and Safely Thaw Them

Why Our Region Is Hard on Pipes

The Philadelphia area's freeze-thaw winters are rough on plumbing: a stretch of mild days lulls everyone, then a single-digit night finds every uninsulated pipe in the house. Rowhome basements, crawl spaces, garage ceilings, and pipes on exterior walls are the usual victims. Water expands about 9% when it freezes, and that pressure is what splits copper and PVC alike — so the best time to deal with frozen pipes is before the cold arrives.

How to Prevent Frozen Pipes in the First Place

• Wrap exposed pipes in unheated basements, crawl spaces, and garages with foam pipe insulation — cheap, and a summer-afternoon job.
• On the coldest nights, let faucets served by exterior-wall pipes drip; moving water resists freezing.
• Open cabinet doors under kitchen and bathroom sinks on outside walls so room heat reaches the plumbing.
• Keep your heating system set to at least 55°F, even when you're away — an off thermostat is how vacation weeks end in flooded basements.
• Disconnect garden hoses and shut off outdoor spigots before the first hard freeze.
• Seal drafts where pipes pass near rim joists and foundation vents, a common weak spot in older masonry homes.

Step-by-Step: How to Safely Thaw a Frozen Pipe

1. Open the affected faucet. Turn on the faucet the frozen pipe serves. This relieves pressure and gives melting ice somewhere to go, which lowers the chance of a burst while you work.
2. Find the frozen section. Trace the line back from the faucet, looking for frost, condensation, or a slight bulge. Check exterior walls, the basement, and crawl spaces first.
3. Know where your main shutoff is. Locate the main water valve before applying any heat. If the pipe has already split, thawing it starts the flood — you want to be able to stop the water in seconds.
4. Apply gentle heat from the faucet toward the blockage. Use a hair dryer, heating pad, or towels soaked in warm water, working along the pipe toward the frozen spot. Never use a torch or any open flame, and keep electrical devices away from standing water.
5. Keep the faucet running as the ice clears. Once flow returns, let the water run for several minutes — moving water melts the remaining ice from the inside.
6. Inspect the pipe for leaks. Check the thawed section and its joints as pressure returns, and again over the next few hours. Hairline splits often only show themselves once water is flowing.

When to Call a Pro

If a pipe has already burst, close the main shutoff and call a licensed plumber immediately. You should also hand things off when the frozen section is inside a wall or ceiling, when the whole house has no water, or when a pipe freezes repeatedly every winter — that's a symptom of an insulation or routing problem worth fixing permanently. And never try to thaw pipes with open flame or an unattended space heater; we see the aftermath of both every winter.

While you're winterizing the basement anyway, it's a good moment for one more piece of cold-weather prep: our guide on how to flush a water heater takes an afternoon and helps your tank survive the heating season.